Hood for collecting gases



Dec. 11, 1951 p p E ETAL 2,578,635

HOOD FOR COLLECTING GASES Filed Jan. 4-, 1950 2 SHEETS-SHEET l INVENTORSPaul Pzerraz 9 Eugene (o/amu Dec. 11, 1951 P. PIERRAT ETAL H000 FORCOLLECTING GASES 2 SHEETSSHEET 2 Filed Jan. 4, 1950 Patented Dec. 11,i951 HOOD FOR COLLECTING: GASES Paul Pierrat and Eugene Colombu, Paris,France; assignorsto La CellophanepaiFrench company Application January4, 1950', Serial No. 136,673

In France'January 13, 1949 3 Claims.

This-inventionrelates to a hood for collecting gases from treatingvessels and particularly to hoods to collect gases from open top tanksused in viscose spinning or casting processes.

object is-to. provide a device of this type which. is sealable to thetank and which may be raised, when. necessary to afiord access tov thetank for service purposes.

Another object is to provide means to remove concentrated gases andrecover usable constituems-therefrom.

Another object is to provide a device of the above type having improveddetails of construction and novel features of operation.

Various other objects andv advantages will be apparent as the nature ofthe invention is more fully disclosed.

Inthe manufacture of thread, films, etc. of regenerated cellulose fromviscose, use is come monly madejof acid baths which give rise to theformation of carbon disulfide and a certain amount of hydrogen sulfide.The liberation of these gases into the atmosphere involves seriousdisadvantages from the point of view of health, apart from anyobjectionable odors, and means have frequently been proposed formitigating these odors and for counteracting the harmfulness of spinninggases. Attempts have also been made to collect the gaseous sulfurcompounds contained in spinning, gases,. and in particular to collectand recover carbon disulfide in the spinning of rayonandstaple fibers,

The present invention provides a device of simple construction andexceptionally efficacious in the collection of gases liberated inviscose treating plants, particularlyin plants manufacturing filmsorspinning and treating continuously staple fiber or rayon, and permitsconvenient recovery of the carbon .disuliide contained in these. gases.

The device consistseessentially of a movable hood having at. least one.suction duct and having one. or more gas inlets. The hood is. connectedby a hydraulic seal, to. close the treating vessel where the gases to becollected are liberated.

The hood may Jae-raised by a hydraulic lift. It may also.be-mechanically counterbalanced for manual operation.

Because of the rapid liberation of the vapors, the degassing vessel, e.g. for a filmgel. in process of'fixation, is'provid'ed with a heatingmeans, for example steam injection nozzles.

The invention-willbe better understood in termsof ,the accompanying,drawings, wherein:

Fig. 1 is. a; longitudinal section of the. first. two tanks of a machinefor the; manufactureof regenerated cellulose films showing the hoodpursuant to the. invention.

Fig. 2 isa transverse section taken onthe. line i Fig.3:;is.a.longitudinal section: similar toFig. 1 showinga furtherembodiment .of' the invention; and:-

4- is.- a transverse section taken on the line 4-4 of Fig. 3.

In. accordancewith the. example of embodiment shownin-Figs. L and 2, thenumeral I designates thefirsttankin a processv for manufacturingreregenera-ted cellulose films, e; gof the type described iniU. S.Patent No. 1,601,289, dated Sep-- tern-her 28th,. 1926. In this tank theviscoseleavingtheslit Sihoi the. casting hopper 3.1 iscQ- agnlated inthe bath 32 to form a wide strip 33'. of gel. This strip is passed.around guides! and 35,. then over rollers 36 and 31 into a second tank.2; containing an acid bath, and then through.

following. tankscontaining Water and in some instancesheated to.--85 C.to 95 C.. by any means, etg. by, nozzles for injectionof steam. The tank2.:may be. divided into apai-r of treating vessels by a partition 38..The tank 2. and. the'following. tanks! contain. series of rollers orother guiding meanst iiand. 5-, conveying. the strip in a zig-zag.

path through the respective baths. The. tank 2 is, .-provided.with slitsv3.9..and 4,0 through which thc-wehpassesintd and. out of a tank.

The ripper-edge of the tank 2,. throughout. its.

lower edge. eta hood lcoverin-g the said tank.

hydraulic. seal.

This hoodis suspended by atv least one hydraulic littingsdevice. 8fixedrat its. upper end to abeam 4.1.. or other support. This. device israised hydraulically or otherwise, to raise the hood sufficiently toafford access tothe. vessel 2 for starting the plant. or for otherpurposes.

The hood 5 has an internal stack 9 surrounding a ventilating-duct [0-,with suction ports H. at the baseandlav damper [2. (Fig. 1) or othermeans otcontrolling thesuction.

Thergasescollected in. the duct it. are carried towa recovery condenser.This device is particularly suitable for the recovery of carbondisulfide bysimple condensation.

The: operation is as follows: After the machine has been started and thestrip of gel passed around the rollers or guides 4 and 5, the hood 1is.- ldwered until its lower edge enters the trough 6, where the wateror other liquid will form-a Suction is then applied to theductclill-byoperating. the' damper ii. If the gel breaks or if themachine is. stopped, the suction. is first shut ofi. the hood is raisedby means of the lifting device 8, and themachine can be restarted.Note-that the suction may be left, onwhile the. hoodis: open to ensureaconstant. supply of fresh air, thus facilitating the operationsof thework, men, in which. case. the suction may be reinforced lay-another andmore powerful blower if desired.

to whether the hood is lowered or raised, the suction being stronger forthe latter position of the hood.

In this embodiment the lower edge of the hood I 3 rests in a hydraulicseal IS on the tank 14, and has a suction duct [6 as in the firstembodiment. There is also a plate I! secured underneath the hood andresting on supports [8. The tank also has a second outlet l9 connectedto a condenser C.

The plate l1, throughout its periphery, is provided with a trough 20filled with water or other liquid to receive a flange 2| attached to thehood l3 and forming a tight seal when the hood is lowered over the tank14.

When the hood i3 and the two hydraulic seals l Sand 20 are closed,suction takes place through the stack l9, and the hydraulic seal 20prevents any intake of gas into the duct I6. When the hood l3 rises, thesuction by way of the stack 19 is shut off, and the duct [8 takes up thenoxious gases, the hydraulic seal 20 being then open. The hood has aneck 22 sliding on the duct "5, which is fixed in this case.

With the use of the devices just described, the required ventilation andconditioning of spinning plants can be greatly reduced. All the noxiousgases are eliminated and working conditions are much improved in ahygienic sense, with a much lower expenditure of heat energy for airconditioning. Moreover, the noxious gases are collected in aconcentrated form, and their treatment either by combustion or forrecovery is facilitated.

Another advantage due to the presence of the hood is that theevaporation of the bath is much reduced, with resulting diminution ofheat losses from this cause, while at the same time the vapors cannot sread through the plant. It is sometimes desirable, in general, toprovide hoods for the subsequent tanks containing hot baths, evenwithout suction, in order to reduce loss of heat energy through vaorization, and to avoid their unrestricted difiusion.

To avoid an accidental dropping of the hood during work, any standardsafety device may be provided.

It may be desirable to flush the interior of the hood or hoods with aninert gas supplied through the inlets 42 after each operation, e. g.with nitrogen, to avoid a mixture of air with gases rich in web throughsaid treating liquid, a movable hood closing the top of said tank, ahydraulic seal extending around the top of said walls, with the loweredge of said hood forming a part of said seal, a stationary suction ductpassing vertically through said head and having ports communicating withthe interior of said tank, a hydraulic lifting device connected to saidhood to lift the hood for access to said tank, said hood having a memberhaving a sliding fit around said duct and movable with the hood tomaintain a gas-tight connection, and means counterbalancing said hoodfor lifting.

2. In a viscose spinning or casting machine, means forming viscose intoa continuous fiat web, side and end walls forming an open top tankcontaining a treating liquid, means feeding said web through saidtreating liquid, a movable hood closing the top of said tank, ahydraulic seal extending around the top of said walls, with the loweredge of said hood forming a part of said seal, a stationary suction ductpassing vertically through said hood and having ports communicating withthe interior of said tank, a lifting device connected to said hood tolift the hood for access to said tank, meansto close said portscomprising a stationary bottom plate having a hydraulic seal extendingaround the area of said ports and a flange on said hood forming a partof said last hydraulic seal when said hood is in lowered position, asecond suction duct communicating with said tank and gas-collectingapparatus connected to said last duct to receive gases when said firstduct is closed by the lowering of said hood.

3. In a viscose spinning or casting machine, means forming viscose intoa continuous flat web, side and end walls forming an open top tankcontaining a treating liquid, means feeding said web through saidtreating liquid, a movable hood closing the top of said tank, ahydraulic seal extending around the top of said walls, with the loweredge of said hood forming a part of said seal, a stationary suction ductpassing vertically carbon disulilde, with possible danger of explosion.

In the case of the machine shown in Figs..1 and 2, the de assing may ofcourse be completed in one or more other tanks with hoods similar tothat described, or in any other suitable arrangement, with immersion ofthe gel in hot water. The ventilating ducts of all the tank may bejoined in a central collector. The hoods in addition t sealing the tanksagainst the escape of fumes permit the gases to be collected inconcentrated form suitable for recovery when the hoods are lowered. Whenthe hoods are raised the suction duct l9 leading to the recoveryapparatus is closed and the dilute gases are removed through the duct16. In this way the dilute gases are prevented from entering therecovery apparatus. Naturally the invention is in no way restricted tothe embodiment shown and described.

What is claimed is:

1. In a viscose spinning or casting machine, means forming viscose intoa continuous fiat web, side and end walls forming an open top tankcontaining a treating liquid, means feeding said through said head andhaving ports communicating with the interior of said tank, a liftingdevice connected to said hood to lift the hood for access to said tank,means to close said ports comprising a stationary bottom plate having ahydraulic seal extending around the area of said ports and a flange onsaid hood forming a part of said last hydraulic seal when said hood isin lowered position, a second suction duct communicating with said tankand gas-collecting apparatus connected to said last duct to receivegases when said first duct is closed by the lowering of said hood, andmeans controlling the suction of the respective ducts.

PAUL PIERRAT.

EUGENE COLOMBU.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Num er Name Date 100,670 Rogers Mar. 8, 1870482,489 Somers et al Sept. 13, 1892 1,819,020 Furness Aug. 18, 19312,053,189 Grauer Sept. 1, 1936 2,061,175 Staber Nov. 17, 1936 2,101,138Gebauer-Fuelnegg et al.Dec. 7, 1937 2,374,535 Gibson -c Apr. 24, 19452,451,890 Ufnowski Oct. 19, 1948 2,488,665 Helm Nov. 22, 1949

